Many new vehicles include systems that provide interactive voice and data services. These systems typically include modems for communicating data, such as automobile status information, and include cellular phones for establishing links to call centers. When activated, a typical vehicle services system establishes a data link with a call center and then communicates data to the call center using a modem. After the data have been transmitted, the system may switch the connection to voice mode by dropping out the modem connection. The system's user may then speak with an operator at the call center. However, once the system drops the modem connection, it may be difficult or impossible to re-establish. Thus, all necessary data must be transmitted before switching to a voice session, which may result in significant delays between activating the system and connecting to a live operator. In addition, current digital cellular networks do not support switching between data and voice modes. Therefore, interactive vehicle services systems generally operate using analog cellular systems, which are often less reliable and more expensive than digital systems.